Capsule for orbiting otolith specimens



July 28, 1970 c. M. BLACKBURN ETAl- 3,521,519

CAPSULE FQR ORBITING OTOLITH SPECIMENS Filed May 6. 1968 8 POWER SUPPLY BLOWER TIMING CIRCUIT l MEMBRANE 66 UNIT H EAT EXCHANGER BARALYME 33 CAN ISTER INVENTORS CHARLES M. BLACKBURN RICHARD S. BRASHEARS FREDERICK A. OYHUS BY w 7 ATTOR United States Patent Office 3,521,619 Patented July 28, 1970 3,521,619 CAPSULE FOR ORBITING ()TOLITH SPECIMENS Charles M. Blackburn, Silver Spring, Frederick A. Oyhus,

Union Bridge, and Richard S. Brashears, Silver Spring,

Md., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed May 6, 1968, Ser. No. 726,797 Int. Cl. A61b /00 US. Cl. 128-2 7 Claims ABSTRACT OF THE DISCLOSURE In order to study accelerative effects induced upon amphibious specimens living in a low gravitational environment, a suitable life support system for such specimens has been provided. The present invention envisions an internally pressurized capsule which provides a waterfilled, specimen-containing compartment which can be rotated by a centrifuge motor, thereby applying an 0.5 g acceleration to the otolith nerves of the specimens. The otolith nerve pulses are recorded and transmitted to a ground receiving station for analysis. The invention provides means for filtering, purifying, and reoxygenating the water supporting the specimens, while also providing temperature control means.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method of and apparatus for providing a life support environment comprising aqueous surroundings for amphibious specimens, which surroundings are continuously temperature-controlled and treated to remove carbon dioxide and to add oxygen. The apparatus includes a specimen container which is rotatable to produce repeated accelerative effects on the instrumented otolith nerves of amphibious specimens which has been orbited into the weightless environs of space.

Sensory, motor, and vegetative disorders of vestibular origin have been observed to occur in men and animals during short periods of weightlessness caused by flying airplanes through Keplerian trajectories. There are several existent hypotheses which attempt to explain these disorders. Common to most hypotheses is the proposition that the disorders produced by weightlessness are related to the otolith system. The present invention enables a direct recording of the otolith responses in a weightless environment.

The data obtained during the experiment should provide information on the adaptability of the vestibule to a sustained weightless environment as well as its response to vibrations and accelerations. Since the otolith system of bullfrogs (Rana catesdiana) is somewhat similar to that in man, and as future manned space flights will require astronauts to remain in a weightless environment for longer periods, the basic information obtained from this experiment may conceivably become an important factor in evaluating astronaut performance.

Description of the prior art Environmental control systems are common in the prior art, ranging from gill type devices such as that disclosed by Bodell in US. Pat. No. 3,333,583 to the purification system of Arnoldi described in U.S. Pat. No. 3,242,651. Such devices do not encompass apparatus capable of providing life-support means for amphibious specimens, provision for stress protection, and means for subjecting the specimens to artificial gravitational effects. Several astronauts have exhibited vertiginous cffects following orbital flights. In order to further understand the reasons for this dizziness, the otolith nerves of two frogs will be instrumented and the frogs orbited aboard a spacecraft. The present invention provides apparatus for sustaining a life support environment and for subjecting the specimens to an artificial gravitational force while in orbit.

The apparatus consists essentially of a lightweight pressure vessel containing a water-filled, cylindrical centrifuge. A life support environment for the frogs is provided by the water which is continuously temperatureco-ntrolled, filtered, and treated to remove carbon dioxide and to add oxygen. Current planning envisions manual actuation of the centrifuge, which will result in a predetermined acceleration being applied to the otolith nerve of each frog. Recorded otolith nerve pulses will be transmitted to ground receiving stations.

It is therefore an object of the invention to provide means for sustaining a compact life supportive environment for amphibious specimens suitable for a prolonged orbital flight and operative in an orbital situation.

It is another object of the invention to provide a watersealed centrifuge in which a life-sustaining environment may be artificially produced.

It is a further object of the invention to provide protection against launching stresses for the specimens and for the delicately positioned instrumentation in the oto lith nerves of the specimens.

Further objects and attendant advantages of the invention will become more readily apparent in light of the following description of the preferred embodiments.

BRIEF DESCRIPTION OF DRAWING The drawing is a schematic view of the preferred embodiment of the invention showing the various systems of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing depicts the preferred embodiment of the invention in schematic fashion, showing the various sys tems and the components composing said systems. The arrangement shown in the drawing exhibits preferred water and gaseous flow paths and treatment. A description of the systems and system components will be given, along with brief mechanical descriptions of the various components as is deemed necessary to an understanding of the invention. In the drawing, a lightweight, nickel-plated, pressure capsule shown at 1 contains an inner assembly structure which consists of upper and lower bulkheads 2 and 4 joined by a cylinder 6, the cylinder 6 fitting into a circular recess at 12 formed in the interior wall of the capsule 1. Between these two bulkheads is a centrifuge 3 which is filled with water and houses the specimens undergoing testing. The centrifuge 3 is rotatably supported by upper bearing 14 in the bulkhead 2 and by a dynamically sealed lower bearing 16 in the bulkhead 4, said bearings being well-known in the art. The bulkhead 2 supports centrifuge motor 5 which rotates the centrifuge 3 in a plane normal to the longitudinal axis of the capsule 1. Drive gears 7 and 9 joined respectively to drive shafts 11 and 13 provide rotational motion transmission from the motor 5 to the centrifuge 3. This rotation will result in a 0.5 g acceleration at the otolith of each of two amphibious specimens 15 contained within the water-filled centrifuge 3. Electrical power necessary to operate the centrifuge motor 5 and other power-requiring equipment is provided by a power supply 17 which, along with the aforementioned associated equipment, is mounted on the bulkhead 2.

Cooperating environmental control devices are attached to the bulkhead 4 in the lower end portion of the capsule 1 and provide water treatment necessary for sustaining a life-supporting environment for the amphibious specimens in the centrifuge 3. The water in which the specimens 15 are immersed is continuously circulated through a system which filters the water, removes carbon dioxide, adds oxygen, controls water temperature, and returns the treated water to the centrifuge 3. Conduits 19 between the various components of this system may be formed of a flexible tubing such as neoprene.

The capsule 1 is fitted with a removable lid 8 which, along with bottom closure 10, is slightly domeshaped to prevent oil canning if pressure reversals should be encountered.

Water from the centrifuge 3 is continuously circulated by a water pump 21 through a thermostat 18, the function of which will be hereinafter described, and on through a filter 23. Suitable filtering material may be A; inch thick, polyurethane sheet foam. Such a filter adds an immeasurably small pressure drop to the water flow and removes all solid contaminants of a size large enough to be visible to the unaided eye. Such filtration is necessary so as not to poison or clog certain other components of the water rejuvenation system.

After filtration, the Water is moved to heat exchanger 24 which maintains the water at a constant life support temperature.

Circulation of the thermally-conditioned water continues to a permselective silicon membrane unit 25, which removes carbon dioxide and adds oxygen prior to returning the water to the centrifuge 3. A small blower 27 receives oxygen from an oxygen supply 29 and transfers the oxygen to membrane unit where the oxygen mixes with carbon dioxide which has passed through a silicon membrane 31 of the unit 25. A certain percentage of the oxygen thus delivered to the unit 25 is immediately absorbed into the water through the membrane 31. However, the majority of the oxygen along with the carbon dioxide present is recirculated between a Baralyme canister 33 where the carbon dioxide is removed from the oxygen circuit, the purged oxygen being returned via the blower 27 to the membrane unit 25 where more of the oxygen is selectively passed into the water. The reoxygenated water is then returned to the centrifuge 3.

The oxygen supply 29 preferably comprises a standard bail out bottle containing oxygen gas at approximately 1800 p.s.i.g. and of such volume as to be adequate for over 100 hours of operation. The storage pressure is reduced to approximately 70 p.s.i.g. by a pressure reducer 35 before entering an aviators demand type regulator 37 which maintains a 1-inch H O (gauge) oxygen pressure at the inlet to the blower 27. The blower 27, used to circulate the oxygen to the membrane unit 25, may be a small diaphragm positive displacement pump similar to the Braillesford VTD-l model. Carbon dioxide is flushed from the membrane unit 25 by the recirculated oxygen and is carried to the Baralyme canister 33 for absorption. Twenty-two cubic inches of Baralyme will remove the carbon dioxide produced by two large frogs in 100 hours.

The requirement for pressure sealing the capsule 1 is easily met by attaching the centrifuge 3, its drive mechanism (i.e., the centrifuge motor 5, gears 7 and 9, and shafts 11 and 13), the power supply 17, and the environmental control apparatus to the aforementioned bulkheads 2 and 4. Attachment of the operative components to the bulkheads allows a system checkout on the bench prior to launch. Following a satisfactory checkout, the assembled bulkheads are lowered into the capsule 1, pertinent electrical connections are made, and the lid 8 is secured in place. An ambient pressure of approximately 15 p.s.i.a. will be maintained in the sealed capsule.

The water in the centrifuge 3 also provides both accelerative and vibrational insulation for the specimens 15. Additional vibrational insulation is provided by isolators 43 located between circular capsule mounting flanges 45, on the outer surface of said capsule, and the spacecraft module shelf 47. Adequate support and restraint of the specimens 15 is necessitated during missile launch and boost phase vibration and acceleration due to the delicate nature of the probes inserted into the otolith nerves of the specimens. Deformation of the tissues surrounding an otolith probe caused by the 6 g longitudinal acceleration produced during boost could conceivably result in pulling the probe from contact with the nerve itself. Since the specimens are submerged in water, the hydrostatic pressures around them are equalized, thus preventing the tissue deformation and possible dislocation of thep robe. The water also provides similar advantageous support during the subjection of the specimens to the artificial 0.5 g acceleration necessary for the experiment.

The life support system of the present invention has been designed to meet the physiological requirements of two frogs weighing approximately 350 grams each. The frogs used are demotorized to prevent them from dislodging the implanted otolith probes and to reduce their metabolic rates. In this condition, the frogs require no artificial respiration and will remain healthy, without being fed, for periods as long as a month. The demotorized frogs are completely submerged in water once they are inserted in the centrifuge of the vessel. The water serves not only as a protection against high accelerations and vibrations but also as the medium which carries oxygen to the skins of the frogs and carries away carbon dioxide.

A thermal control system consists of an evaporator pan 51, a thermostatically controlled water metering valve 53 of the solenoid type, a cooling Water supply 55, the heat exchanger 24, and the nickel plating of the capsule 1. The evaporator pan 51, located on the opposite end of the capsule from the removable lid 8, is provided with a valve 59 set at .11 p.s.i.a. The cooling water supply 55 is also located on the same end but in a rubber bladder 61 inside the pressure tight capsule. Thermal coupling between the evaporator pan 51 and the heat exchanger 24 is accomplished through the capsule 1 with an indium foil gasket 63 between said capsule and the pan 51, to reduce contact resistance. An indium foil strip 64 separates the heat exchanger 24 from the Wall of the capsule 1.

In operation, a thermostat 18 contacting the lift support water demands cooling when the temperature of the water goes above 58 degrees F. The closing of the thermostat 18 actuates a timing circuit 66 so that the solenoid valve 53 opens periodically at fixed intervals for fixed lengths of time, both intervals being adjustable. As a result of the residual seal level ambient pressure inside of the capsule 1, water is forced through the valve 53 into the evaporator pan 51 where it is evaporated at the low ambient pressure (.11 p.s.i.a.) and by the internal heat loads. Saturation temperature of water at this pressure is about 37 degrees F.; therefore, heat can flow from the heat exchanger 24 to the evaporator pan 51. The life support water is circulated through the heat exchanger 24 and when the temerature is lowered enough to open the thermostat 18, the valve 53 is closed, and no more cooling water flows. The successful operation of this system depends upon (1): one correct flow rate during cooling, (2): reduction of contact resistances, and (3): the polished nickel plating exterior of the pressuretight capsule. The first insures that the cooling will be adequate in the hottest expected environment and in the coldest expected environment will not allow excess water to accumulate in the evaporator pan 51, causing an overshoot in cooling action. The second is to provide a good path for heat to flow from the heat exchanger 24 to the pan 51, and the third insures minimum heat exchange with environment outside the pressure vessel.

It is believed apparent that the present invention is not limited to the particular construction prescribed in the embodiments shown, it be considered that minor changes in construction may be permitted within the scope of the appended claims.

What is claimed is:

1. A method of providing a life-supportive environment for amphibious specimens in which gravitational effects may be induced on the specimens in an otherwise weightless environment, comprising the steps of providing a water-filled enclosure to contain the specimens,

purifying the water contained within the enclosure by removing the carbon dioxide given off by the specimens,

rejuvenating the life-supportive capacity of the water contained within the enclosure by adding oxygen to the water,

controlling the temperature of the water at a level suitable to the maintenance of life of the specimens, and

rotating the specimen containing enclosure around a central axis, thereby producing an accelcratory effect on the specimens.

2. The method of claim 1, and further comprising,

circulating the water contained within the enclosure through life-supportive means,

filtering the water to remove solid impurities,

maintaining the water at a temperature suitable to maintain life of the specimens,

removing from the water carbon dioxide given off by the specimens through normal respiration, absorbing the removed carbon dioxide, and

adding to the water life-sustaining oxygen.

3. The method of claim 2, and further comprising instrumenting the otolith nerves of the amphibious specimens contained within the enclosure, recording the data produced by acceleratory affects on the specimens during weightlessness, and

relaying said data to earth for analysis.

4. Apparatus for providing a rotatable, life-supportive environment for amphibious specimens by which the specimens are subjected to acceleratory effects during weightlessness, comprising container means for holding the specimens in an aqueous environment,

filtration means associated with said aqueous environment for removing solid impurities from the aqueous environment,

rejuvenative means associated with said aqueous environment for replenishing oxygen to the aqueous environment,

purgative means associated with said aqueous environment for removing carbon dioxide from the aqueous environment,

thermal control means associated with said aqueous environment for maintaining the aqueous environment at a temperature suitable to the health of the specimens, and

propulsion means connected to said container for rotating the specimens at a measured acceleration.

5. The apparatus of claim 4 wherein said rejuvenative means comprise a water circulative system which directs water from the specimens container for oxygen addition and which returns the water to said container after such oxygen addition is effected,

oxygen storage and supply means for containing the oxygen needed to support the life functions of the specimens and for supplying the oxygen to the water in said water circulative system for absorption by the water, and

membrane means for selectively allowing passage of supplied oxygen into the water at a rate suitable to dissolution of the oxygen into the water.

6. The apparatus of claim 4 wherein said purgative means comprise a water circulative system which directs water from the specimens container for carbon dioxide removal and which returns the water to said container after the carbon dioxide is removed,

membrane means for selectively allowing the passage of carbon dioxide out of the water being drawn from the enclosure,

directive means for transporting the purged carbon dioxide from the vicinity of the water, and

means for absorbing the purged carbon dioxide in order to prevent its accumulation in gaseous form.

7. The apparatus of claim 4 wherein said thermal con- 5 trolling means comprise thermostatic means located in contact with the water in the water circulative system,

a cooling water supplying means,

a valve connected to said cooling water supplying means,

a valve timing circuit connected to and operable by the thermostatic means to open said valve periodically at a fixed interval for a fixed length of time,

an evaporator pan connected to receive the water passed through the valve and including means for evaporating the water under low pressure, and

a heat exchanger associated with said aqueous environment through which is circulated life-supportive water from the specimen-containing enclosure and which thermally communicates with the evaporator pan, thereby allowing heat transfer from the heat exchanger to the evaporator pan, thus cooling the life supporting water and influencing the thermostatic means to close the valve and discontinue the cooling water flow.

References Cited UNITED STATES PATENTS RICHARD A. GAUDET, Primary Examiner K. L. HOWELL, Assistant Examiner US. Cl. X.R. 

